Rotary converter.



i ATENTED MAR. 171908. N9 882531" Lnmnanoez. -P

ROTARY CQNVBRTER.' Aryruourox'gunn' $111.28, 190e'.

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Tij-3 l www@ ATTORNEYS JOHN l.. Ml'lilltllli, (lli BUUNDBROUK, NEW JERSEY.

ROTARY CONVERTER.

Specification of Lettera Patent.

i Patented March 17, 1908.

Application filed March 28, 1906. Serial No. 308,477.

To all. whom 'it may concern.:

Be it known that I, JonN l.. Mitanook, a citizen of the United States, and a resident of Boundbrook, in the county of Somerset and State of N ew Jersey, have invented a new and Improved .Rotary Converter, oi which the following is a full, clear, and exact description.

My invention relates to so-called Hcurrent shaping mechanism, my more particular object being to produce a rotary converter, for selecting from three-phase alternatingcurrents predetermined portions of said currents, in suoli manner as to accumulate the effect of the portions thus selected, and thus build p a virtually direct current which is practically constant.

My invention further relates to certain details of construction incidental to carrying out the object above stated, and particularly to mechanism for 'accomplishing the follow- 'ing purposes; to 'witz 1. To avoid sparking at the brushes used for the direct current. 2. To provide a broad bearing surface for the 'direct current brushes, the entire bearing surface being as completely available as possible. 3. '.lo stop the flow of currents through the armature independently` of the breaking action of the brushes relative to the sectors,

thus rendering it'impossible for a spark to take place when a sector leaves a brush. 4. To dispose the brushes, eld magnets, sectors and wire connections, in such manner that the relation of the various parts'one to .an-

oth-er may be determined by knowing the position -ot any one of said parts. 5. To employ upon the direct current side of the converter, two groups of commutatoi` sectors and brushes arranged relatively thereto in 40 such manner that one brush always receives positive current from one group of sectors, vWhereas the other brush always receives negative current from the other grou of sectors. 6.' To place the direct current rushes exactly on top of the rotatin i commutator sector-rings, in order that sai brushes may be readily accessible. 7. To give thedirect current sectors and the direct current brushes such relative mathematical proportions as 50 will attain increased efliciency 1n the converter as a whole.

Reference is to be had to the accompanying drawings forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the figures.

Figiue 1 is a side elevation, part-lysis.-

grammatic, showing the rotary converter as connected with and controlled by a threephase alternating line supplied by a threephase alternating generator; Fig. 2 is an en- 6G,

larged elevation of the converter, viewed. as

from the left oi Fig. 1, the pedestal for supporting the armature shaft being. partly broken away 5 Fig. 3 is an enlarged fragmentary elevation of the direct current commutator rings and the carbon brushes communicating therewith, the view being somewhat simil ar to the corresponding part at the right in Fig. 1, Fig. 4 is a plan view of the mechanism shown in Fig. 3, showing more particularly the connection ofthe carbon brushes 50, 51 with the binding posts 61 and 62 and direct current mains 52 and .56 Fig. 5 is an enlarged section through two sectors, one,l sector being in the positive sector ring, the other being inv the negative sector ring, the two sectors being connected by a wire 47 5 Fig. 6 is a diagrammatic elevation of the positive' sector ring made up ofthe sectors 39, 40, 41 and engaged by the brush', the view represent- 80 ing the arts as they would be seen from the left of igs..3 and 4 and showing a brush 50 as engaging the center of the sector 41; Fig.N 7 is a corresponding view of the negative sector' ring built up of the sectors 42, 48, 44 engaged 35 by a brush 51., Fig.. 8 shows the same mechanism as Fig. 6 but with the positive sector ring in a slightly ldiiferent position; Fig. 9 is a view ysimilar to Fig. 7, showing the same mechanism but With the negative sector ring moved into a relatively different position, an-d Fig. 1p is a diagranr of the wiring and other electrical connections of the entire systern. Referring more particularly to Fig. 1, a 95 pedestal 11 at the .transmitting station sup-l ports the armature shaft 12 of va three-phase alternating generator. Mounted upon this armature shaft are the usual slip rings 18, 14, 15 which are .engaged by the respective brushes 17, 18, 19, the latter being supported upon anarrn 16 oi insular/ino' material in the usual, or in .any preterre manner. rEhe three-phase l alternating currents from the brushes 17, 19 are received'and transmitted b Wires 2G,21, 22 to the receiving station sr own at -`the right in Fig. 1. The wires 20, 21, 22 here connect, respectively,

with brushes 23, 24, 2.5 supported by an arm 26 of insulating material. Bearings 27, 27a mounted upon pedestals 27 bsu port the revoluble armature shaft 28 of t e rotary converter at the receiving station indicated by the right hand portion of Fig; 1. Slip rings 29, 30, 31 are engaged directly by the brushes 23, 24, 25 in the usual manner. These slip rings. 29, 30, 31 are connected, respectively, with armature windings 32, 32", 32 separated by insulation 32. Each winding 32, 32", 32c occupies, therefore, one-third of the revoluble armature, as will be understood frni Fig. 2. The connection from the slip rings 29, 30, 31 to the respective windings 32, 32", 32c is made separately by means of leads 33, 34, 35, as indicated in Fig. 10. From the windings, wires 36, 37, 38 lead respectively to4 sectors 39, 40, 41, constituting the positive sector ring, shown diagrammatically in Figs. 6 and 8. The three other sectors 42 43, 44 are assembled to ether so as to formthe negative sector rings own in Figs.

' tively connected with the sectors 42, 43, 44 by 7 and 9. The sectors 39, 40, 41 are respecineans of connecting wires 45, 46, 47, as indicated in Fig. 10. Plates 48 of insulating material are sandwiched between thesectors 39, 40, 41, and simi'a'l'y lates 4.2, 43,44, are separated bv in ulating p ates49.

The brushes rareshown at 50,51, and are supported by anA arm 26a and the brushes are of such dimensions that each occupies exactly one-sixth of the circle represented by the sectors engaged by the brush.l As

u necessarily each sector talres up substantially exactly one-third of the circle, or in other words, as each sector is of 120 degrees, it follows that eachl brush represents an arc of vdegrees and occupies one-half the distance represented by the length of a sector. The sectors 39, 40', '41, constitutin the positive sector ring, are staggered re atively to the sectors 42, 43, 44, constituting the nega'-.

tive sector rin The result ofthis arrangement is that W en one of the brushes, for instance 50, rests directly uppn the center of a sector, such as 41, (see ig; 6), the other brush (say 51) rests with one-half of its length upon each of two sectors, say 42, 43. The amount of surface, therefore, engaged by any brush is substantially uniform at all times. For instance, as shown in Figs. 5, 6,

`7, 8, 9, a brush must at any given moment,

occupyeither one-half of a sector, or two fragmentary portions of two sectors, aggregating a surface equal to one-half of a sector.

Since, as above stated, the sectors constihitin the negative sector ring are staggered re ative to the sectors constituting th positive sector ring, it follows "that eac/lei negative sector is diametrically o positegan opposingl sector, as 4indicatedin igs. 3.a1id 5'. Eac positive sector. being therefore connected with the negativesector exactly opposite thereto as indicated in Fig. 5, it follows that when a brush, such as 50, engages any particular one of the posivtive sectors (say, for instance, 41), the nega- `negativ mams 55, -machine the direct current is supplied to the tive sector (for instance, 44) being diametrical thereto', must necessarily be out of enagement with its brush 51. There is, thereore, no danger of a current assing through the brush 50 'and a sector 41 irectly into any sector connected with the brush 51. From the br'ush 50a wire 52 leads to field magnets 53, 54, the latter being connected with a main 55. This main, together with a main 56 connected with the 'brush 51, constitutes the 'two direct current terminals for supplying electric energy to the line or to the machine in which the direct current is required. Generally speaking, therefore, a three-phase alternating current issupplied by three wires to the alternating current side of the converter, represented by the right hand portion of F1g. 10, and from the positive and 56 'at the other end of theV point where it is needed.

The brushes 50, 51 are held by metallic casings 57, 58, being steadied thereupon by gina 59, 60 passed directly into the brushes.

inding, osts 61, 62 communicate with the brushes t ough the metallic casings 57 58 and are in turn connected with the wires 52,

56, as indicated in Figs. 3 and 4.

Referring to4 Fig. 2, it will be noted that the field magnets 53, 54 are located respec. tively below and above the armature shaft 28 and exactly in diametrical alinement with the' brushes. This arrangement is very convenient as it enables the various o erators to ascertain in an instant the exact e ectric condition of any part of the armature or of any sector, by merelyv noting its angular displacement relative to thatof the field magnets. The arrangement of the parts above described is such that the armature windings 32, 32", 32c are positioned exactly in alinement with the sectors 39, 40, 41, and are consequently exactly opposite the sectors 42, 43, 44; hence, when a particular winding 32, 32b or 32C is passing through the densest of the magnetic fields, that particular winding can be in direct communication with only one of the brushes 50 or 51. Su pose, for instance, that in Fig. 10 the win( ing 32u is passing throu h the densest portion of the magnetic fiek?, and' consequently that the brush 50 rests upon the center of the sector 41 if by this arrangement positive Vcurrent is sent into` thegbrush 50 and consequently thro ,fthe'iielsV 53, 54 to the line 55, it is selfevident that this same winding 32c cannot be at the same moment sending current directly through the other brush 51. Suppose now, that the positive current formed within the winding 32c passes as just indicated, through the sector 41, brush 50, wire 52, fields 53 54 to the direct current line 55, and then u on doing its work, flows backl as a so-calle negative current through the main 56 and into the brush51; it next passes through sector 42, wire 45, sector 39, wire 36 and winding 32", thence back to the alternating generator. From this it will be seen that when a ycurrent flowing in a particular direction is generated within the winding 32", and this current is diverged tothe direct current lino, the return current can flow back and at least one other winding, such as 32a, is in proper condition to receive'the return current and start it backward, in proper phase, to the generating station. If it should happen that one of the brushes 50 or .il should engage two sectors, the other brush engaging only one, this makes no dil'- lerence l'or the reason that the current flow ing between the brush andthe one sector isy exactly er ual to the current flowing between the other ln'ush and the two sectors engaged by it. ln this connection it Inay'be noted that in a three-phase system, no matter what may be the direction or the current intensity in a particular wire representing one of the three phases, the sum of the efl'ects in the other wires each representing a phase, is necessarily equal to it, and opposite in direction.

The operation yof my system is as follows: Suppose, aswould naturally be the case, that the wires 20, 21, 22 are energized successively. in such order as to become positive in succession and also to become negative' in succession, we will assume, for instance, that a cui rent is flowing through the wiref22 into thc ring 31, and this, of course, im lfes that one or more currents equal in vo tage and an'iperage to the current flowing in through brush 25, and flowing in the opposite direction oiut through brush 23 or 24, or both brushes 23 and 24, as the case may be. The course ol the so-called positive current entering the converter is as follows: brush 19 at transmitting station, (see Fig. 1 left hand), wire 22, brush 25 of converter, `slip ring 31, wire 35, winding 32, wire 33, positive sector 4l (sector 43 being now out of communication with brush 5l) brush 50, wire 52, field windings 53, 54 to main55 of line, thence returning to main 55, brush 51, negative sector '12, positive sector 39 (now dead, being outl ol conlnlunication with brush 50) Wire 36, winding 32, wire 33, slip ring 29, brush 23, back through wire to source of alternating current supply. lt will be seen that the current thus sent through the mains 55, 56 of the direct current line flows outward through brush 5f) and inward through brush 51. 'A inonn-rnt later and the rotation of the armature, ol' the. converter causesethe sector 41 to more partially out from under the brushf50,

and likewise causes the sector 39 to make engager-nein' with the brush 50. This same degree ol' rotatimi causes the sector 42 to move coniphflel; out lroin under thebrush 51 and causes the ybrush 43 to move beneath this brush, as indieatedn Fig. 9. This degree of rotation, it will lie noted, is just suflicxent to through the other brush 51.

cause current to flow through the wire 20 and the wire .22 toward the converter, and also to causea current of opposite direction to flow through the wire 21. That .is to say: the current flowing through wire 21 toward. the alternating generator is exactly equal to the -surn of the two currents flowing through wires 21, 22 toward the converter. A

'l he circuit now completed is a's follows: wires 20, 22,l,rushes 23, 25, slip rings 29, 31, wires 33, 35, windings'32, 32", wires 36, 38, sectors 39, 41, (both now engaging brush 50) thence through lrush 50, wire 52, field windings 53, 54 to direct current line, thence re turning through wire 56, hrush 51, sector 43 (this being the sole sector now engaging l. rush 51), w ire 46, sector 40, (now dead, being now out of engagement with brush 50), wire 37, winding 32", wire 34, slip ring 30, brush 24 and w ire 2] hack to the source of alternating current. In this instance, as iefore, the current flows outward l'ro1n.l:rush 50 and inward through brush 51. Further rotation of the'armature causes brush 50 to rest centrally upon sector 39 and causes brush 51 to engage sectors 43, 44, When this occurs, the circuit is completed as follows?` A current flows from the generator and v. ire 20 into ly rush 23 and slip ring 29, thence through wire 33, e inding 32a, u ire 36, sector 39 (now incontact with brush 50), brush 50, wire 52, lield" windings 53., 54, direct current main 55 to ling, thence returning by niain 56, brush 51, sec'- tors 43, 44 (now engaging brush 51) thence in parallelito wires 46, 47 to sectors 40, 41 (now dead, leing out ol' communication with lzrush 50), wires 37, 38, windings 32, 320, wires 34, 35, slip rings 30, 31, brushes 24, y and thence through wires,21,22 hack to the source of alternating current supply.

I-t w ill thus he seen that nomaltei in w hat ie, if any` :urrent whatever passes throng these windings, it necessarily7 goes out through the'hrush 50 to the direct current line, and returns through brush 51. Hence, I consider the sectors 39 40, 41 as' positive sectors and the sectors 42, 43, 44 as negative sectors. f

It is true that each sector is constantly changing its sign; but this fact is immaterial for the reason that whenever a sec-tor 39, or 41 engages the brush 50, that sector at that instant is necessarily positive. If two of these sectors engage the brush at the same instant, the two sectors taken together are pgsjtive relative to the current passing Similarly, whenever any one of the sectors 42, 43, 44 is in engagement with the brush 51, at that particular instant the sector thus in engagement is necessarily negative; that is to say,-the current need not necessarily he flowing at that particular instant; but if it flows at all in any part of the sector it necessarily always osition the windings of the armature ma il i .vs in the same direction through the brush 50 and in the opposite direction through the brush 51; and if the current divides, as above pies Y no current is generated in the winding during -this moment.

' spective brushes 50,

explained, so as to 'pass in one direction through a plurality of sectors, and in the positive direction through a single sector, the positive and negative currents necessarily balance each other in passing throughthe reto Fig. 2, it will'be noted that the wlnding 32c is passin through the densest part of the magnetic ii'e d, and conseq`uently is energized to a maximum extent.

Referring now .'lhis occurs at the exact instant whend the brush rests centrally u on the sector 41,'as

indicated in Fig. 6, this eing the same instant that the brush 51 rests partly upon the sector 42 and the sector 43, as indicated in Fig. 7. Such being the case, the current passing outward through brush 50 to the direct current line returns to brush 51 and there splits, as indicated in Fig. 7, so as to return through sectors 42, 43. An instant later,l however, the several sectors assume the positions indicated,in Figs. 8 and 9. The

`sector 42 is now just leaving the brush 51, and of course this' fact would' seemingly indicate that a spark might occur as between the brush 51 and the sector 42. Why Y does not this spark occur? Simply because the partial rotation of the armature shaft 28 has moved the winding 32 a small fraction of a revolution and the winding 32" consequently arrives at a point l,in the magnetic ield when the number of lines of force is neither increasing or decreasing, and consequently no current whatever for the moment is generated in the winding 32a.

yReferring again to Fi 2, it will be noted that if the armature siaft 2S be rotated `slightly in the direction the arrow, the

32a must assume such a position windin where 1t is acted upon equally by ,the two fields, and consequently the lines `f force thron h it are neither increasing or c oreasing. n other words: the Winding 32a occufor a moment a neutral position, and

any spark can occur between'any brush and Y' any sector at an';v part of the revolution of the armature. he fact is, the current in any particular winding gradually rises to' its maximum and gradua ly dies away to nothing. Since, however, there are three of these windin there is no particular instant of time w en the current is not owing throu h at least two of them. in other words: t e

direct current flows continuously sometimes y through only two of the windings and sometimes through all three of them, yet each .windin becomes neutral-twice during each revolution of the armature; and whenever a winding becomesneutral, this occurs at the rec'ise instant necessa to prevent sparking etween the sectors an their brushes.

Haying thus described my invention I claim as new and desire to secure by Letters Patent:

In a three-phase rotary converter, the combination'of a stationary field, an armature provided with three windings, two sec# tors connected with' each winding, each-of said sectors representing approximately 120 degrees of a circle, and two brushes each" having a contact length representing a proximately degrees of a circle' an being adapted to rest throughout said Contact length upon one or more of said sectors;

. ln testimony whereof lhavg signed, my naine to this specification in the presence of twofsubscribing witnesses.

Witnesses:

Ron'r. T. BnAMProN, JAooB F amai'. 

